[Asterisk-video] MP4Play async Audio / Video

Thomas Z. mobilemail at gmx-topmail.de
Tue Sep 25 08:52:16 CDT 2007


Hi Sergio,

thank you very much. The result with the Helix Mobile Producer is much
better.
But we need a software runs on a Linux environment.
Can you support us with a another linux software?

Regards
Thomas


Sergio Garcia schrieb:
> You coulde try with qt encoder or the helix mobile producer.. 
>
> ---------- Original Message ----------------------------------
> From: "Thomas Z." <mobilemail at gmx-topmail.de>
> Reply-To: Development discussion of video media support in Asterisk<asterisk-video at lists.digium.com>
> Date:  Tue, 25 Sep 2007 10:52:07 +0200
>
>   
>> Hello Sergio,
>>
>> do you know a freeware or cheap CBR encoder?
>>
>> Regards
>> Thomas
>>
>> Sergio Garcia Murillo schrieb:
>>     
>>> Hi Thomas, Thomas and Ratmin.. :)
>>>  
>>> Back to work form a long abroad weekend (nice Belgium!)
>>>  
>>> As Ratmin has stated the Skew indication would help to indicate the
>>> handset the delay between audio and video.
>>> It's usually used to correct fixed delays introduced by internal
>>> jitter buffers and thinks alike. The problem that Thomas
>>> Z. is suffering seems to be produced by using ffmpeg for video
>>> encoding (as Thomas without Z points :)
>>> The problem is the following, ffmpeg is a great VBR (variable bit
>>> rate) encoder, but I've not been able to behave like a
>>> CBR (constant bit rate) encoder. The problem is that it's prepared for
>>> movies, not for streaming, and defenitevilly not
>>> at this low bitrates.
>>> The inner loop of the encoder always tries to encode ALL macroblocks
>>> in a frame, so in I frames and at a very low
>>> bitrate it simply just can't get a small amount of data for that frame
>>> and when it's enqued into h324m it takes more
>>> than one frame time to send (sometimes even more than a second), the
>>> following frames are small and sent after
>>> that until the queue is empty, which causes a fast-forward effect
>>> on some handsets. As you can imagine adjustime
>>> audio to that scenary is jus impossible (even with the Skew Indication
>>> the result would be horrible!!)
>>>  
>>> The good solution: use a CBR encoder :)
>>> The not so good solution: drop packets when the queue is filled, but
>>> you'll end up dropping all the frames between
>>> each I frame.. but in that case it would be much better to lower the
>>> video fps...
>>>  
>>> BR
>>> Sergio
>>>
>>>     ----- Original Message -----
>>>     *From:* Ramtin Amin <mailto:keytwho at hotmail.com>
>>>     *To:* Development discussion of video media support in Asterisk
>>>     <mailto:asterisk-video at lists.digium.com>
>>>     *Sent:* Monday, September 24, 2007 2:01 PM
>>>     *Subject:* Re: [Asterisk-video] MP4Play async Audio / Video
>>>
>>>
>>>
>>>
>>>     RTSP has timestamp... so you can usually know how to sync the
>>>     audio/video
>>>     But the problem would be more that we'll need to add a Skew
>>>     Indication concept inside asterisk's core so it could make the
>>>     message go throught the different channel/application, as it is
>>>     currently done for VideoFastUpdatePicutre... Which means that
>>>     currently, if a SIP channel receives a VideoFastUpdatePicture, it
>>>     is capable of resending it to an other channel...
>>>
>>>      
>>>     ------------------------------------------------------------------------
>>>
>>>     > Date: Mon, 24 Sep 2007 13:48:54 +0200
>>>     > From: mobilemail at gmx-topmail.de
>>>     > To: asterisk-video at lists.digium.com
>>>     > Subject: Re: [Asterisk-video] MP4Play async Audio / Video
>>>     >
>>>     > Hello Ramin,
>>>     > hello Thomas.
>>>     >
>>>     > I think both ways are possible. But I don't know if it easy to
>>>     implement.
>>>     > Sergio, what do you think about it?
>>>     >
>>>     > Is this also a problem if we stream the audi/video via rtsp?
>>>     >
>>>     > Regrads
>>>     > Thomas
>>>     >
>>>     >
>>>     > Ramtin Amin schrieb:
>>>     > > hello
>>>     > >
>>>     > > The way I solved this problem was by sending a H223SkewIndication
>>>     > > message to the other terminal
>>>     > > Acutally, You will have to ask Sergio to add a H245 indication
>>>     message
>>>     > > of type h223SkewIndication and when playing the video with
>>>     mp4play, he
>>>     > > will have to see the difference of timing between Video and
>>>     Audio and
>>>     > > then send this value to the remote terminal so the lip sync
>>>     would work...
>>>     > >
>>>     > >
>>>     > >
>>>     > > **
>>>     > >
>>>     > > *2.3 Multipoint Lip Synchronization*
>>>     > >
>>>     > > In a multipoint VC, each terminal may transmit different
>>>     > >
>>>     > > //
>>>     > >
>>>     > > /H223SkewIndication /message for associated video and
>>>     > >
>>>     > > audio channels in H.223 protocol. To enable lip
>>>     > >
>>>     > > synchronization at receiving terminals, MCUs will
>>>     > >
>>>     > > transmit accurate /H223SkewIndication /messages. MCUs
>>>     > >
>>>     > > may accomplish this by adding delay to equalize the
>>>     > >
>>>     > > audio/video skew for all transmitting terminals. When
>>>     > >
>>>     > > switching between broadcasting terminals, H.223 may
>>>     > >
>>>     > > transmit a new /H223SkewIndication /message reflecting the
>>>     > >
>>>     > > audio/video skew of the current broadcaster.
>>>     > >
>>>     > >
>>>     > > --
>>>     > > Ramtin Amin
>>>     > >
>>>     > >
>>>     > >
>>>     > >
>>>     > >
>>>     ------------------------------------------------------------------------
>>>     > >
>>>     > > > From: thomas.frieling at viif.de
>>>     > > > To: asterisk-video at lists.digium.com
>>>     > > > Date: Mon, 24 Sep 2007 11:48:12 +0200
>>>     > > > Subject: Re: [Asterisk-video] MP4Play async Audio / Video
>>>     > > >
>>>     > > > Hi Thomas Z!
>>>     > > >
>>>     > > > I think this problem is due to the bitrate restriction on 3G
>>>     calls. The
>>>     > > > audio stream is always sent immediately while the video
>>>     stream has to
>>>     > > > use what is left of the bandwidth. This is why videos become
>>>     synchrous
>>>     > > > again when the video bitrate is pretty low for a while in
>>>     the video...
>>>     > > >
>>>     > > > Take a look at this discussion:
>>>     > > >
>>>     > >
>>>     http://lists.digium.com/pipermail/asterisk-video/2007-September/001257.html
>>>     > > >
>>>     > > > One solution is to reencode every video with a low bitrate
>>>     and use a
>>>     > > > fixed bitrate encoder (ffmpeg is dynamic bitrate for
>>>     example). I had the
>>>     > > > impression though that this still doesn't always work,
>>>     especially when
>>>     > > > the UMTS connection is not too good...
>>>     > > >
>>>     > > > My idea is that we check each time before sending a keyframe
>>>     if there is
>>>     > > > already a new keyframe in the queue. If this is the case, we
>>>     jump to the
>>>     > > > most recent keyframe and just drop the data before that.
>>>     > > >
>>>     > > > What do you think about this? How hard to implement?
>>>     > > >
>>>     > > > Regards,
>>>     > > > Thomas F
>>>     > > >
>>>     > > >
>>>     > > >
>>>     > > > Am Montag, den 24.09.2007, 11:15 +0200 schrieb Thomas Z.:
>>>     > > > > Hello,
>>>     > > > >
>>>     > > > > We have the problem, that a converted mp4 file is
>>>     asynchronous via 3g
>>>     > > > > network.
>>>     > > > > If we play the file on a pc, everything is synchron.
>>>     > > > > We tried already to reduce the quality and framerate of
>>>     the video. But
>>>     > > > > nothing helps.
>>>     > > > >
>>>     > > > > Is it a problem with mp4play or with the video?
>>>     > > > >
>>>     > > > > What can we do to get the audio and video synchronized via
>>>     3g network?
>>>     > > > >
>>>     > > > > Thank you,
>>>     > > > > best regards
>>>     > > > > Thomas
>>>     > > > >
>>>     > > > >
>>>     > > > >
>>>     > > > > _______________________________________________
>>>     > > > > --Bandwidth and Colocation Provided by
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>>>     > > > --
>>>     > > > www.ViiF.de - your Mobile Video Community
>>>     > > >
>>>     > > > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>>>     > > >
>>>     > > > Thomas Frieling - IT Development
>>>     > > > ViiF Mobile Video GmbH, Poststr. 21-22, 10178 Berlin
>>>     > > > Cell: +49 (0) 173 63 62 62 3
>>>     > > >
>>>     > > > mailto:thomas at ViiF.de
>>>     > > >
>>>     > > > Sitz: Berlin, Amtgericht Berlin-Charlottenburg, HRB: 108350B
>>>     > > >
>>>     > > > Geschäftsführer: Daniel Höpfner, Steffen Brünn
>>>     > > >
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